class School:
    def __init__(self,name):
        self.name=name
        self.department=[]
        self.student=[]
    def department_add(self,department):
        self.department.append(department)
    def student_add(self,student):
        self.student.append(student)

class Department:
    def __init__(self,name,school):
        self.name=name

        self.school=school
        self.school.department_add(self)

        self.instructor=[]
    def instructor_add(self,instructor):
        self.instructor.append(instructor)

class Instructor:
    def __init__(self,name,department):
        self.name=name
        self.department=department
        self.department.instructor_add(self)
        self.course=[]

    def course_add(self,course):
        self.course.append(course)

class Course:
    def __int__(self,name):
        self.name=name
        self.instructor=[]

    def instructor_add(self,instructor:Instructor):
        self.instructor.append(instructor)
        instructor.course_add(Instructor)

class Student:
    def __int__(self,name,school:School):
        self.name=name
        self.school=school
        self.course=[]

    def course_add(self,course:Course):
        self.course.append(course)
